1. Field of the Invention
The present invention relates to an audio signal processing apparatus, audio signal processing method and imaging apparatus suitable for the application for recording surround 5.1 channel audio signals, for example.
2. Description of the Related Art
In the past, various audio players have been proposed for enjoying audio of a radio program or on a music CD (Compact Disc) or a DVD (Digital Versatile Disk), for example, indoors. These audio players can play a surround-recorded sound source by using a surround technology for implementing a sound field similar to a movie theater or a surround technology for implementing a sound field similar to a music hall.
For example, a (5.1 channel) surround system in the past has five channel speakers of, about a listener, Front Left (FL) and Front Right (FR) at the front, rear left Surround Left (SL), rear right Surround Right (SR) and Front Center (FC) and a 0.1 channel sub woofer (SW). This surround system implements the surround playback in sound supporting 5.1 channels around a listener.
By the way, in order to implement the surround playback, surround recording in sound suitable for the speaker characteristics is desired when recording. In the past, various recording technologies have been used for implementing the surround sound recording.
JP-A-5-191886 (Patent Document 1) discloses a surround sound microphone system that collects sound in 360° sound source directions through a first microphone having non-directivity and a second to fourth microphones having directivity exhibiting cardioid curves.
JP-A-2002-232988 (Patent Document 2) discloses a multi-channel sound-collecting apparatus that synthesizes five directional microphone sounds having directivities of the front left, front right, rear right, rear left and front from the output of three non-directional microphones.
JP-A-2002-218583 (Patent Document 3) discloses a field sound synthesis computing method and apparatus, which corrects the sensitivity for a low frequency of a near sound and uses an extracted near sound to reduce touch noise and/or wind noise.